I owe them nothing. I've already given them money for the game, what more do I "owe" them? Money, mind you, that they held onto for six weeks while I waited on a face import patch so I could play my own Shepard(s). A patch, mind you, that DID NOT WORK. For a feature that should have worked from day 1. I had to rely on a fan-fix to get my Shep into the game. The one that Bioware claimed their patch accurately represented.
You say oh, they're working hard on the DLC! Well, that's speculation. A word this fourm just loves, but, really, that's all it is. Speculation. They could have 2 guys working on it in the afternoons before they head home, which is why it'll take so long, for all you know.
Extending something doesn't make it better. If you have a fever, and you feel awful, will having a longer, higher fever be even better? No. No it won't.
Also, don't even compare Valve to Bioware. They aren't even in the same league. Valve would never have screwed something up this badly, nor left critical issues in the game broken for this long. SO many bugs, story errors, import problems, faces still awful, laundry list of problems.
That said, Valve hasn't "had you" on a "cliffhanger" for HL3. They've never even announced such a game is being made, and generally only even hint at the possibility of it. If they say they're making something, they do, and they are not afraid of holding it back for months, or even years, to make sure it's exactly what they want it to be. (Such as TF2). They don't rush things out before they're done.
Even if the EC and every non-cashcow...I mean "multiplayer" DLC is a total love letter to fans (instead of a love letter to EA shareholders), Bioware is still going to be climbing up a very, very tall hill.
If you alienate your fanbase enough, you can make all the DLC you please, but it doesn't mean anyone's going to buy it. Wouldn't doubt the DLC of ME3 will go the same route as the DLC from DA2. Disappear.